The present invention pertains to novel thermosettable polymeric cyanates.
Thermosettable aromatic or bridged aromatic cyanates and the polytriazines resulting from curing of said cyanates are known in the prior art, for example, as taught by German Pat. Nos. 1,190,184; 1,195,764 and 1,720,740. In U.S. Pat. No. 3,694,410, a variety of polymeric dicyanates of the structure NC--O--R--O--CN with R being an oligomeric chain of bridged aromatic nuclei are taught. These dicyanates, however, suffer in reactivity upon curing due to the presence of the large bridging (R group) structures which inherently lower the density of curable cyanate groups. Further, the properties of these cured compositions become largely dependent upon said bridging (R group) structures rather than the polytriazine functionality, per se. As is emphasized in U.S. Pat. No. 4,094,852, the moisture sensitivity of the prior art polytriazines is unacceptably high.
The present invention provides polymeric cyanates of high reactivity and useful cured compositions via homopolymerization to the polytriazines. Copolymerization of these polymeric cyanates with difunctional cyanates of the prior art provides polytriazines with improved mechanical and thermal chemical properties and reduced moisture sensitivity. Copolymerization of these polymeric cyanates with epoxy resins provides useful cured compositions containing both triazine and oxazoline structures. These resins are useful in the preparation of laminates, castings, coatings and the like.